1. Field of the Invention
The present invention relates generally to the finishing of various viscous or plastic materials before hardening into a cured state. More particularly, the present apparatus relates to an attachment for an angle grinder or other power source that relieves a user from the necessity of having to finish the surface of concrete, plaster, mortar, drywall compound, and similar viscous substances by hand.
2. Description of the Related Art
Concrete is a mixture of cement, water and aggregates, such as sand or gravel. These components are mixed together and then poured over a surface. For some applications, after concrete has been poured it is desirable to finish the concrete in order to get a smooth, even finish. Finished concrete would be desirable in such places as garage or basement floors or on concrete countertops.
Finishing concrete is a skilled and delicate task. Traditionally, finishing concrete was done with hand trowels. Before newly poured concrete fully sets, typically at the point where finger pressure can just dent the surface of the concrete, hand troweling with a steel hand trowel would begin. To achieve a finished surface on concrete all of the surface pores must be closed. Usually this is accomplished by using a hand trowel. The skilled aspect of finishing concrete lies in the fact that the worker must take care not to disturb the larger areas of aggregate that lie below the surface. If the larger areas of aggregate that lie below the surface are disturbed, the concrete is subject to premature deterioration.
Many different varieties of machines exist to finish concrete and are generally referred to as “troweling machines.” A typical troweling machine will have between a 5.5 and 8.0 HP motor, a plurality of fixed pitch blades, and a handle used to maneuver the machine and control the speed of the motor. A disadvantage to troweling machines is their substantial weight. Even when a troweling machine is used to finish a large surface area, such as a garage floor or other enclosed slab, hand trowels must still be used to finish the edges of the floor where a large troweling machine, with its relative lack of maneuverability, cannot reach. For raised or smaller surfaces, such as a concrete countertop or concrete steps, a person must use hand trowels, since a troweling machine would not be practicable. The related art does not provide any tools or methods that would enable a person to finish concrete in small, confined spaces, or in hard to reach edges, without resorting to hand trowels. Moreover, a tool or apparatus capable of providing more versatile use for finishing other plastic materials in addition to concrete, e.g., plaster, drywall compound, mortar, stucco, etc., is highly desirable.
Various devices have been designed for finishing concrete. U.S. Patent Publication No. 2003/0217743, published Nov. 27, 2003, shows a method and apparatus for removing trip hazards in concrete sidewalks. The apparatus is coupled to an angle grinder, but is used to cut a chamfer into a concrete slab, rather than to finish a non-hardened concrete surface. U.S. Pat. No. 5,372,452, issued Dec. 13, 1994 to James A. Hodgson, teaches a power trowel featuring blades made of spring steel. The blades on the power trowel are generally rectangular rather than triangular. The power trowel is also designed for finishing large open floor areas, unlike the present invention, which discloses a tool that can be used with an angle grinder or other prime mover.
U.S. Pat. No. 5,911,620, issued Jun. 15, 1999 to Rolf Spangenberg et al., describes a pot-shaped grinding wheel that is coupled to an angle grinder. The pot-shaped grinding wheel features segment-like grinding surfaces and a different overall shape from the present invention.
Other concrete finishing devices, angle grinder attachments, and related devices are shown in U.S. Patent Publication No. 2002/0025224, published Feb. 28, 2002 (concrete-finishing apparatus), U.S. Pat. No. 4,281,496, issued Aug. 4, 1981 to Jan O. Danielson (method of forming concrete floors and product of the method); U.S. Pat. No. 4,865,227, issued Sep. 12, 1989 to Anthony L. Stephens (dispensing apparatus); U.S. Pat. No. 5,468,176, issued Nov. 21, 1995 to Karl E. Udert et al. (disk-shaped tool bit for an angle grinder); U.S. Pat. No. 6,021,771, issued Feb. 8, 2000 to Leo Swan et al. (surfacing machine with “strip-sert” cutter assemblies); U.S. Pat. No. 6,058,922, issued May 9, 2000 to Marvin P. Sexton (grinding blade for trowel machine); U.S. Pat. No. 6,139,217, issued Oct. 31, 2000 to Bruce W. Reuter (concrete finishing tool); U.S. Pat. No. 6,264,397, issued Jul. 24, 2001 to Charles Majewski (dual trowel. blade assembly); U.S. Pat. No. 6,299,522, issued Oct. 9, 2001 to Chang Hyun Lee (grinding wheel for use in grinding apparatus); U.S. Pat. No. 6,527,634, issued Mar. 4, 2003 to Chang Hyun Lee et al. (grinding wheel with segments for preventing one-sided wear); U.S. Pat. No. 6,533,650, issued Mar. 18, 2003 to Takuma Yoshida et al. (grinding stone); and U.S. Pat. No. 6,637,974, issued Oct. 28, 2003 to J. Brandall Glenn (roller wall guard for floor finishing machines).
European Patent No. 535,431, published Apr. 7, 1993 shows an angle grinder with a disk-shaped abrasive disk.
Finally, the website “hongsui.com/566689” referenced on Mar. 29, 2004 provided a disclosure of a thirty-six inch diameter power trowel powered by a 5.5 horsepower engine and controlled by a handlebar assembly extending therefrom.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a surface finisher solving the aforementioned problems is desired.